Trauma is the leading cause of death in Americans between the ages of one and forty years. Shock lung, the pulmonary insufficiency that can follow severe trauma and shock, is a major cause of death in patients who are initially successfully resuscitated from their injuries. The objective of this proposal is to analyze the role of arachidonic acid metabolites (including the native prostaglandins) in the pathogenesis of shock lung. Radioimmunoassays for the breakdown products of the principal arachidonic acid metabolites, thromboxane A2 and prostacyclin, are being set up to assay samples from: 1) a clinical study of the effect of PGE1 infusion on the clinical course of patients with terminal respiratory failure of shock and trauma; and 2) a collaborative animal study of the arachidonic acid metabolites present in lung lymph of sheep subject to hemorrhagic septic insult and burns.